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Tightening torque thermostat housing 6.9

Started by Jan S, 22 November 2021, 08:01 AM

Jan S

Engine M100.985 6.9

Anyone have information on the tightening torque of:

- the four M6 bolts on the thermostat cover-to-housing?
- the two M12 bolts on the thermostat housing-to-water pump?

Steel bolts and aluminum alloy threads.

Any tips would be welcomed.
1975-mod W116 450 SE with 6.9 engine


     You may find info in the Forum Library.   I have the M117 service manual .  ::)
Neglected ~ Rescued ~ 1977 450SEL 4.5L  U.S.A. ver.
Project of Compassion ~ Respect
Silver Green Metallic / Toast
Left Hand Drive
Sliding Roof


'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,

Jan S

Thanks, TNNBenz, I found the tightening torque for the two M12 bolts, with 8.8 grade If I remember correctly = 23 Nm ("Thermostat housing to coolant pump bearing housing") - on page 158 in the "Manual_100-985_Mechanical_04_82.pdf".

Thanks, rumb, great table in general. However, it seems that the torques in the table you forwarded are too high compared to the workshop manual, probably due to the soft aluminum threads?

I couldn't find the torque for the four M6 bolts. Probably around 10 Nm?

1975-mod W116 450 SE with 6.9 engine